1. Field of the Invention
The present invention relates to an object detection apparatus.
2. Description of Related Art
It is known to equip a vehicle with distance sensors such as ultrasonic sensors to detect an object present in the vicinity of the vehicle, such as a preceding vehicle, a pedestrian, or an obstacle to enable performing various control operations such as starting of a brake apparatus, or notification to a vehicle driver in accordance with results of the object detection for the purpose of increasing running safety of the vehicle.
When an object is present outside a vehicle width area of the vehicle, the risk of a collision between the vehicle and the object is small. However, if only the distance between the vehicle and the object is measured without detecting the position of the object in the vehicle width direction perpendicular to the running direction of the vehicle, it may be determined that there is a risk of a collision with the object and the vehicle driver is informed to that effect, although the object is present outside the vehicle width area.
Japanese Patent Application Laid-open No. 2014-89077 describes an object detection apparatus for detecting a position in the vehicle width direction of an object which is ahead of a vehicle on which the object detection apparatus is mounted. This object detection apparatus includes two distance sensors mounted on a vehicle, and calculates the position of an object in the vehicle width direction using a triangulation method. This object detection apparatus determines that there is a risk of a collision with the object when the calculated position is within a vehicle width area of the vehicle, and determines that there is no risk of collision with the object when the calculated position is outside the vehicle width area. This object detection apparatus is capable of preventing a brake apparatus from being operated when there is no object within the vehicle width area.
However, the object detection apparatus described in the above patent document has the following problem. This object detection apparatus can detect only one object per one object-detection cycle. More specifically, when a plurality of objects are present ahead of the vehicle, the object detection apparatus detects only one of the objects which is the closest to the vehicle, but cannot detect the other objects. Accordingly, in a situation where the closest object is outside the vehicle width area, but another object which is more distant from the vehicle than the closest object is exists within the vehicle width area, there is a concern that the brake apparatus does not operate although there is a risk of a collision.